1. Field of the Invention
The present invention relates to an airbag apparatus mountable on a top plane of the instrument panel in front of the front passenger's seat and including an inflatable airbag.
2. Description of Related Art
JP 2006-96322 A is illustrative of a conventional airbag apparatus provided for a front passenger's seat. This airbag apparatus includes an airbag that is provided with an exhaust hole openable upon contacting an occupant seated very close the instrument panel (namely, a “nearby occupant”). The exhaust hole is comprised of a gap of a lap portion where base cloths forming the circumferential wall of the airbag overlap. When the airbag contacts the nearby occupant in the course of inflation, the base cloths on the lap portion separate from each other and provide the exhaust hole to allow venting of inflation gas. When the airbag completes inflation, the inner pressure of the airbag and the tensile force exerting over an entire circumferential wall of the airbag due to the inner pressure make the base cloths on the lap portion contact each other and closes the exhaust hole.
The exhaust hole of the above reference is located on a top area of the airbag as fully inflated. Conventionally, a top-mount airbag for a front passenger's seat is folded up and housed in a housing located on an interior of a top plane of an instrument panel. In operation, the airbag once protrudes upward and unfolds and expands rearward in the space between the top plane of the instrument panel and a windshield. If the conventional airbag described above is mounted on a compact car which has a small space between the instrument panel and windshield, the airbag as activated may stuff the space when a nearby occupant contacts the instrument panel. In that case, it is possible that an area around the exhaust hole is pressed onto the windshield and the opening of the exhaust hole is obstructed.